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2005 St. Johns River Water Management District (SJRWMD) Lidar: Western Seminole County, Florida

This data set consists of a bare earth data set of 498 files covering a geographic area of 175 square miles in western Seminole County, Florida and includes small portions of adjacent Orange and Lake Counties. The lidar data was collected June 5-7, 2005. This data set seems to contain only model keypoints (points that are a thinned data set that is intended to remove extraneous data such as trees and points that are deemed redundant to the final bare earth product) that are classified as ground points. As a result, there are a lower number of points than in a full mass point lidar data set; and it is recommended that the data be downloaded as points and used with a TIN (Triangulated Irregular Network) or similar algorithm to produce a bare earth surface.

Cite this dataset when used as a source.

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    Distribution Formats
    • LAZ
    Distributor DOC/NOAA/NOS/CSC > Coastal Services Center, National Ocean Service, National Oceanic and Atmospheric Administration, U.S. Department of Commerce
    Point of Contact St. Johns River Water Management District (SJRWMD)
    386-329-4542
    GIS_Support@sjrwmd.com
    Associated Resources
    • Lidar Dataset Supplemental Information
    Originator
    • DOC/NOAA/NOS/CSC > Coastal Services Center, National Ocean Service, National Oceanic and Atmospheric Administration, U.S. Department of Commerce
    Originator
    • St. Johns River Water Management District (SJRWMD)
    Publisher
    • DOC/NOAA/NOS/CSC > Coastal Services Center, National Ocean Service, National Oceanic and Atmospheric Administration, U.S. Department of Commerce
    Date(s)
    • publication: 2005-08-01
    Data Presentation Form: Digital image
    Dataset Progress Status Complete
    Data Update Frequency: Unknown
    Purpose: This data set depicts information about geographic features within the project area and is to be used for purposes defined by the SJRWMD.
    Use Limitations
    • These data depict the elevations at the time of the survey and are only accurate for that time. Users should be aware that temporal changes may have occurred since this data set was collected and some parts of this data may no longer represent actual surface conditions. Users should not use this data for critical applications without a full awareness of its limitations. Any conclusions drawn from analysis of this information are not the responsibility of NOAA or any of its partners. These data are NOT to be used for navigational purposes.
    Time Period: 2005-06-05  to  2005-06-07
    Spatial Reference System: urn:ogc:def:crs:EPSG::4269 Ellipsoid in Meters
    Spatial Bounding Box Coordinates:
    N: 28.875263
    S: 28.639242
    E: -81.240467
    W: -81.486743
    Spatial Coverage Map:
    Themes
    • Bathymetry/Topography
    • Lidar Mapping
    • Topographic
    • Bare earth
    • Intensity image
    • LAS
    • ASCII
    Places
    • United States
    • Florida
    • Western Seminole County
    • Portions of Orange County
    • Portions of Lake County
    Use Constraints No constraint information available
    Fees Fee information not available.
    Lineage Statement Lineage statement not available.
    Processor
    • Aerial Cartographics of America, Inc.
    • DOC/NOAA/NOS/CSC > Coastal Services Center, National Ocean Service, National Oceanic and Atmospheric Administration, U.S. Department of Commerce
    • DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department of Commerce
    Processing Steps
    • LiDAR Data Acquisition -- The Lidar data was collected utilizing an Optech ALTM (Airborne Laser Terrain Mapper) 2025 in a Cessna 208 Grand Caravan aircraft on June 5, 2005 between 0930 and 1150 hours at an altitude of 3000' AGL. Data was also collected starting June 6, 2005 at 1830 hours and ending on June 7 at 0900 hours. The configuration used a scan half-angle of +/-17 degrees, a laser pulse repetition frequency of 25 kilohertz, and a flying speed of approximately 80 knots. Airborne GPS using a Novatel dual frequency GPS receiver was accomplished during the flight session to provide positional information for the Lidar platform. Simultaneous acquisition of ground base station data was performed using a Novatel and Leica SR9500 dual frequency receivers for the June 5, 2005 session. Two Leica SR9500 dual frequency GPS receivers were used for the second session on June 6-7, 2005. Each station remained in operation for the duration of the project flight. The ground base stations were set up over National Geodetic Survey (NGS) monuments AK0205 (Designation Number I4 71 A14) and AK7045 (Designation Number GIS 0472 CAS 1). Positional information on these monuments was obtained from Data Sheets retrieved from the NGS website (http://www.ngs.noaa.gov). The GPS data from the ground base stations and the airborne platform were processed together using Applanix POSPac 4.2 software module POSGPS. All adjustments were referenced to WGS84. The Inertial Measurement Unit (IMU) solution was accomplished to provide information regarding the attitude of the Lidar platform using the Applanix POSPac 4.2 software module POSProc. This solution was integrated with the Airborne GPS and adjusted using a Kalman filter in a forward/reverse solution to provide a Smoothed Best Estimate of Trajectory (SBET). Laser ranging from the airborne platform was accomplished using Realm 3.2 processing software to provide XYZ ground positions for each point. The final horizontal values were output in Universal Transverse Mercator (UTM), Zone 17, units are meters. The horizontal datum conforms to the current Florida High Accuracy Reference Network (HARN) adjustment for the North American Datum of 1983. The Vertical Datum is the North American Vertical Datum of 1988 (NAVD88), units are feet.
    • Classification of the laser data to extract above ground features such as buildings and vegetation leaving only bare earth ground points was performed using Terrasolid Ltd. Terrascan software (Version 003.003). The data was separated into five (5) separate sets 502 files representing Bald Earth First Pulse, Bald Earth Last Pulse, Extracted Features First Pulse, Extracted Features Last Pulse, and LAS format. The Bald Earth Last Pulse best represents the natural ground and is the file upon which all accuracy statements are based. The Extracted Features First Pulse best represents the canopy data that includes all features determined to be above the natural ground.
    • The NOAA Coastal Services Center (CSC) received the bare earth files in ASCII format. The data were Universal Transverse Mercator (UTM), Zone 17, units in meters, NAVD88 vertical datum and the vertical units of measure were feet. CSC performed the following processing to the ASCII data to make it available within Digital Coast: 1. The data were converted from UTM coordinates to geographic coordinates. 2. The data were converted from NAVD88 (orthometric) heights to GRS80 (ellipsoid) heights using Geoid 03. 3. The LAS data were sorted by latitude and the headers were updated.
    • The NOAA National Geophysical Data Center (NGDC) received lidar data files via ftp transfer from the NOAA Coastal Services Center. The data are currently being served via NOAA CSC Digital Coast at http://www.csc.noaa.gov/digitalcoast/. The data can be used to re-populate the system. The data are archived in LAS or LAZ format. The LAS format is an industry standard for LiDAR data developed by the American Society of Photogrammetry and Remote Sensing (ASPRS); LAZ is a loseless compressed version of LAS developed by Martin Isenburg (http://www.laszip.org/). The data are exclusively in geographic coordinates (either NAD83 or ITRF94). The data are referenced vertically to the ellipsoid (either GRS80 or ITRF94), allowing for the ability to apply the most up to date geoid model when transforming to orthometric heights.

    Metadata Last Modified: 2013-05-07

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